I just purchased the large bag by Frontier Natural Products, and not having previously tasted cacao nibs I didn't know what to expect. When I received it in the mail, I noticed that the bag had a small puncture, but I tried them anyway. The taste was bitter and what I am guessing to be the taste of rancid nibs. I thought they were so nasty that I had thrown them away.
Yet, I've heard how delightful the taste of cacao nibs were, so I went ahead and tried TerrAmazon brand. The taste of TerrAmazon is 5x better than Frontier Naturals. No bitter taste and really delicious.
If this is your first time trying cacao nibs, they are not sweet. Just nutty with the smell of rich chocolate and crunchy texture. I add them to a homemade trail mix that includes nibs, mulberries, raisins, cashiews, pistachios, and goji berries.

I bought the nibs to sprinkle in my trail mix - what a great addition. They are slightly sweet and add a nice hint of chocolate. Not sure I could eat too much entirely on their own as they are a bit bitter (as is any unsweetened cocoa) but they are a great little flavour complement.

When I first tried these, I was a little taken aback as it was a lot more bitter than I anticipated, however I have now grown to love them. If you are expecting a taste like chocolate chips you will be dissapointed though! They are much more bitter, and like concentrated cacao powder. I love them in my porridge for an antioxidant hit in the mornings and a slight chocolatey taste.